This invention relates to apparatus for assisting a boatman to navigate a waterway. More specifically, this invention relates to apparatus for indicating to a boatman on which side of a buoy he should pass in order to remain in the channel that is being marked by the buoy.
The channels in navigable waterways are marked on one side by black buoys and on the other side by red buoys. However, the red and black buoys do not always occur in pairs, so it is necessary for a boatman to know on which side of a red or black buoy he should pass in order to remain in the channel marked by the buoy. Depending upon the direction being travelled and the particular waterway, the boatman may have to pass either to the port and starboard of a black buoy or to the port and starboard of a red buoy. At the beginning of a trip the boatman can determine from charts and the like to which side of any given buoy he is supposed to pass. However, it often happens that this information is forgotten during the trip, and the boatman may be required to make a quick decision whether to pass to the port and starboard of a red or black buoy. If the wrong choice is made, the boatman's boat may not remain in the channel and may become grounded or even may sink.
Devices for indicating on which side a buoy should be passed are not generally new. Reference may be made, for example, to U.S. Pat. No. 2,633,818, issued Apr. 7, 1953, Harold S. Garrett and to U.S. Pat. No. 4,050,400, issued Sept. 27, 1977, Nelson Tatton et al.
The devices shown in the Garrett and Tatton et al patents do not operate based on differences in colors of channel marking buoys, but rather operate on the basis of the difference in shape of a can buoy and a nun buoy. The Garrett patent discloses an arrangement in which models of buoys of the same shape as a nun buoy and a can buoy are mounted on a rotatable turret, the position of which is adjusted before a trip depending on whether the boat is travelling upstream or downstream. The buoys are illuminated, but only in response to activation of a searchlight on the boat. No color distinction between the buoys is drawn. In the Tatton et al patent a movable slide member is disclosed carrying at both ends thereof representations of a nun buoy and a can buoy. The slide member can be moved behind a disk having apertures therein, the components being so arranged that when a nun buoy is seen through one aperture, a can buoy will be seen through the other aperture, and vice versa. The representations of the buoys are illuminated by lights, but there is no indication that any distinction is made based upon different colors of the buoys. It is disclosed in the Tatton et al patent that red and green lenses are provided, but this is only for the purpose of indicating which of two boats has the right of way.
Not all buoys marking navigable waterways may be shaped as can buoys or nun buoys but, generally speaking, channels always are marked by buoys that differ in color, red and black being the two selected colours, as previously indicated.
The instant invention thus is a very simple piece of equipment which can be set at the beginning of a trip to clearly indicate whether a black buoy should be passed on the starboard or port and the same for a red buoy.